Time Travel

 

Back In Time

Don't bet your future
On one roll of the dice
Better remember
Lightning never strikes twice
Please don't drive at eighty-eight
Don't want to be late again

Are there rules for time travel?

Time travel has fascinated storytellers for a very long time.  And IMHO time travel is possible, but you can’t change much about the past, so you may not want to time travel.

If the future has not been written, that is because there are choices that have yet to be made in the future, but choices have already been made in the past.  Just as there is a probability cone of future events that becomes wider as the time from that event increases, there is also a past in which those choices have already been made, so for the same distance in the past from that event, the probability cone is much narrower, and you are confined to visit only the past which could lead to the current choices.  Thus you can’t travel back in time and assassinate Hitler before WWII or prevent him from being born, because you come from a reality where Hitler was born and started WWII.  You can visit Hitler, but your actions can’t change the present from which you started.  You can’t also guarantee a win in tomorrow’s lottery because that has not yet happened. 

This sounds a lot like the time travel rules that existed in Superman comic books from 1949 to 1984.  Superman could visit the past, but he could not change the past.  Superman writers followed those rules because otherwise if Superman could travel to the past then why wouldn’t Superman change the past.  You also can not get to a past that is not in your past.  The South winning the Civil War might be one of the Multiverses, but we can not travel from our reality to a past where the South won the Civil War because the South did not win the Civil War in our reality. We can only visit what has happened, not what might have happened. 1.21 Giga Watts!!! What was I thinking?